UV-C transparent glass and glass components

Abstract

To provide UV-C transmitting glass with good meltability, low coefficient of thermal expansion, and excellent water resistance in a specific composition of aluminoborate-based glass. [Solution] In mass%, SiO2: 46.90% or more and less than 55.00%, B2O3: greater than 27.00% and 35.10% or less, Al2O3: 6.90% or more and 12.00% or less, Li2O: 0.90% or more and 8.00% or less, Na2O: 0.90% or more and 8.10% or less, K2O: 0% or more and 5.10% or less, R2O: 4.00% or more and less than 9.00% (however, R2O represents the sum of Li2O, Na2O and K2O), MgO: 0% or more and 3.00% or less, CaO: 0% or more and 3% UV-C transparent glass characterized by containing 0.00% or less of solids, SrO: 0% to 4.00%, BaO: 0% to 4.00%, R'O: 0% to less than 5.00% (where R'O represents the sum of MgO, CaO, SrO, and BaO), Sb2O3: 0% to 1.00%, F: greater than 0.01% and 1.00%, and Cl: 0.05% to 1.00%, with a mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) less than 0.1.

Description

[Technical Field]

[0001] This invention relates to UV-C transmitting glass and glass components. [Background technology]

[0002] Traditionally, low-pressure mercury lamps emitting ultraviolet light at 184.9nm and 253.7nm have been used as light sources for sterilization purposes. However, due to the Minamata Regulation on Mercury, an international treaty concluded in 2013, the manufacture, import, and export of mercury-containing products have been prohibited since 2021, with the exception of some exempted items. As a result, there has been growing interest in UV-C LEDs (deep ultraviolet LEDs) as an alternative to low-pressure mercury lamps, as they have a lower impact on the human body and the environment. Furthermore, the spread of COVID-19 has increased the need to disinfect objects touched by many people on the spot, and UV-C LEDs, which are easy to use and compact, have rapidly gained popularity as a new market.

[0003] However, while mercury lamps have an output of several watts to tens of watts per lamp, UV-C LEDs have an output of several milliwatts to tens of milliwatts per element. Therefore, UV-C LEDs are still in the development stage in terms of output. In the future, as the efficiency of electricity and photovoltaic power generation improves and the output of UV-C LEDs exceeds 100 mW, UV-C LEDs will have an extremely strong germicidal effect and will be able to be implemented in large-scale UV-C devices that were previously handled by mercury lamps.

[0004] As UV-C LEDs become more powerful, UV-C LED packages require greater durability. UV-C LED packages utilize window components, such as flat plates or lenses. The lens-shaped window component protects the UV-C LED chip from the outside air and also controls the light emitted from the UV-C LED, enabling efficient UV-C irradiation.

[0005] Quartz glass, with its excellent UV-C transmittance and durability, has been considered suitable for use as a window component in UV-C LED packages. However, the manufacture of quartz glass requires melting the raw materials at temperatures above 2000°C. Furthermore, processing of quartz glass involves machining by cutting and polishing from ingots. Therefore, quartz glass has problems with productivity and processability.

[0006] On the other hand, aluminoborosilicate glass has a lower melting temperature than quartz glass, and some varieties exhibit high transmittance over a wide wavelength range. Therefore, aluminoborosilicate glass can be useful as a glass for UV-C LED packages.

[0007] For example, Patent Documents 1-4 disclose aluminoborosilicate glass that is transparent to ultraviolet light. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 4-342437 [Patent Document 2] Japanese Patent Publication No. 2018-197190 [Patent Document 3] Japanese Patent Publication No. 2012-140314 [Patent Document 4] Japanese Patent Publication No. 2013-230952 [Overview of the project] [Problems that the invention aims to solve]

[0009] From a productivity standpoint, good meltability is essential for UV-C transmitting glass. However, the glass disclosed in Patent Document 1 has poor meltability, and its manufacture may require melting the raw materials at high temperatures. Furthermore, poor meltability can lead to poor bubble removal, potentially resulting in bubbles remaining inside the glass. In addition, the glass disclosed in Patent Document 2 is particularly preferably made to contain 60-68% by mass of SiO2 as its main component, which may result in poor meltability due to the large amount of SiO2.

[0010] It is crucial that UV-C transmitting glass has a low coefficient of thermal expansion. For example, UV-C LED packages typically use ceramics such as aluminum nitride (AlN) or alumina (Al2O3), which have high thermal conductivity, as the housing material. Because the thermal conductivity of glass and ceramics differs significantly, a large temperature difference occurs between the glass and the ceramic housing when heat is applied to bond them. Therefore, if the thermal expansion coefficient of the glass is high, distortion may occur within the glass, potentially leading to breakage defects. However, Patent Documents 3 and 4 do not address the coefficient of thermal expansion at all.

[0011] Since UV-C transparent glass is required to function as a encapsulant that protects the UV-C LED chip from moisture in the outside air, good water resistance is also essential. Furthermore, if the glass has poor water resistance, it may react with water, causing cloudiness and potentially reducing UV-C transmittance. However, Patent Documents 2 and 4 do not address water resistance at all.

[0012] In light of the above, UV-C transmitting glass is required to satisfy all of the following requirements, particularly through optimization of its composition: good meltability, low coefficient of thermal expansion, and excellent water resistance.

[0013] Therefore, the present invention has been made in view of the above circumstances, and aims to provide a UV-C transmitting glass with good meltability, low coefficient of thermal expansion, and excellent water resistance in a specific composition of aluminoborosilicate glass. Another object of the present invention is to provide a glass component using the above-described UV-C transmissive glass. **Means for Solving the Problems**

[0014] As a result of intensive studies to achieve the above object, the present inventors have found that the above problems can be solved in a specific composition of aluminoborosilicate glass, and have completed the present invention. The gist of the present invention for solving the above problems is as follows.

[0015] [1] In mass%, SiO2: 46.90% or more and less than 55.00%, B2O3: More than 27.00% and 35.10% or less, Al2O3: 6.90% or more and 12.00% or less, Li2O: 0.90% or more and 8.00% or less, Na2O: 0.90% or more and 8.10% or less, K2O: 0% or more and 5.10% or less, R2O: 4.00% or more and less than 9.00% (where R2O represents the sum of Li2O, Na2O, and K2O), MgO: 0% or more and 3.00% or less, CaO: 0% or more and 3.00% or less, SrO: 0% or more and 4.00% or less, BaO: 0% or more and 4.00% or less, R’O: 0% or more and less than 5.00% (where R’O represents the sum of MgO, CaO, SrO, and BaO), Sb2O3: 0% or more and 1.00% or less, F: More than 0.01% and 1.00% or less, Cl: 0.05% or more and 1.00% or less and a UV-C transmissive glass characterized in that the mass ratio represented by (R2O + R’O) / (SiO2 + B^2O3 + Al2O3) is less than 0.1.

[0016] [2] The average coefficient of linear expansion (α -7 ) is 45 × 10 -7 / ℃ or higher 60×10 -7 UV-C transmitting glass as described in [1], which is below / ℃.

[0017] [3] UV-C transmitting glass according to [1] or [2], wherein the internal transmittance at a wavelength of 265 nm at a glass thickness of 1 mm is 90% or more.

[0018] [4] A UV-C transmitting glass according to any of [1] to [3], wherein the glass transition temperature is 510°C or lower.

[0019] [5] A UV-C transmitting glass according to any one of [1] to [4], wherein the glass piece is 20 mm x 10 mm x 10 mm, and when the glass piece is boiled in 1000 ml of pure water for 60 minutes, the weight loss before and after the boiling treatment is less than 0.1% by mass.

[0020] [6] UV-C transparent glass as described in any of [1] to [5], for precision mold press molding.

[0021] A glass component characterized by using UV-C transparent glass as a material, as described in any of [7] [1] to [6]. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide UV-C transparent glass with good meltability, low coefficient of thermal expansion, and excellent water resistance in a specific composition of aluminoborosilicate glass. Furthermore, according to the present invention, it is possible to provide glass components using the UV-C transmitting glass described above. [Modes for carrying out the invention]

[0023] (UV-C transmitting glass) The UV-C transmitting glass of one embodiment of this invention (hereinafter sometimes referred to as "the glass of this embodiment") will be described in detail below. The glass of this embodiment is In mass%, SiO2: 46.90% or more and less than 55.00% B2O3: more than 27.00% and less than 35.10%, Al2O3: 6.90% or more and 12.00% or less, Li2O: 0.90% or more and 8.00% or less, Na2O: 0.90% or more and 8.10% or less, K2O: 0% or more and 5.10% or less, R2O: 4.00% or more and less than 9.00% (however, R2O represents the sum of Li2O, Na2O, and K2O). MgO: 0% or more and 3.00% or less, CaO: 0% or more and 3.00% or less, SrO: 0% or more and 4.00% or less, BaO: 0% or more and 4.00% or less, R'O: 0% or more and less than 5.00% (where R'O represents the sum of MgO, CaO, SrO, and BaO). Sb2O3: 0% or more and 1.00% or less, F: more than 0.01% and less than 1.00%, Cl: 0.05% or more and 1.00% or less It is characterized by containing (composition requirement) [the following]. Furthermore, the glass of this embodiment is characterized in that the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1. The glass of this embodiment was discovered by the inventor through repeated experiments, and while satisfying the above compositional requirements, the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is less than 0.1, making it possible to provide UV-C transmitting glass with good meltability, low thermal expansion coefficient, and excellent water resistance in a specific composition of aluminoborosilicate glass.

[0024] The reasons for the limitations on the range of each component in the composition requirements are as follows. Unless otherwise specified, "%" in relation to components refers to "mass%".

[0025] <sio2> SiO2 is an essential component in the glass of this embodiment and is the main component that forms the network structure of the glass. SiO2 is a component that can lower the coefficient of thermal expansion and improve water resistance. Furthermore, SiO2 is a component that can improve devitrification resistance stability. However, if the SiO2 content is 55.00% or more, the viscosity of the glass melt will increase, and there is a risk that the meltability will decrease significantly. On the other hand, if the SiO2 content is less than 46.90%, there is a risk that the effect of lowering the coefficient of thermal expansion and improving water resistance will not be sufficiently obtained. There is also a risk that the effect of improving devitrification resistance stability will not be sufficiently obtained. For this reason, in the glass of this embodiment, the SiO2 content was set to a range of 46.90% or more and less than 55.00%. From a similar viewpoint, it is preferable that the SiO2 content in the glass of this embodiment be 47.00% or more, and also preferable that be 54.90% or less.

[0026] <b2o3> B2O3, like SiO2, is a component that forms the network structure of the glass in the optical glass of this embodiment. B2O3 is a component that can reduce the viscosity of the glass melt without changing the thermal expansion coefficient of the glass, thereby improving meltability. Furthermore, B2O3 is a component that can enhance devitrification resistance stability. However, if the B2O3 content exceeds 35.10%, there is a risk that the water resistance will deteriorate. On the other hand, if the B2O3 content is 27.00% or less, there is a risk that the viscosity of the glass melt will increase, and the effect of improving meltability will not be sufficiently obtained. For this reason, in the glass of this embodiment, the B2O3 content was set to a range of more than 27.00% and less than or equal to 35.10%. From a similar viewpoint, the B2O3 content in the glass of this embodiment is preferably 27.50% or more, and preferably 35.05% or less.

[0027] <al2o3> In the glass of this embodiment, Al2O3 is a component that can lower the thermal expansion coefficient of the glass and improve its water resistance. Furthermore, Al2O3 is a component that can suppress phase separation of the glass and improve devitrification resistance stability. However, if the Al2O3 content exceeds 12.00%, the meltability of the glass may deteriorate. On the other hand, if the Al2O3 content is less than 6.90%, the effect of lowering the thermal expansion coefficient of the glass and improving its water resistance may not be sufficiently obtained. Also, if the Al2O3 content is less than 6.90%, phase separation of the glass may not be suppressed, and devitrification resistance stability may be significantly reduced. Therefore, in the glass of this embodiment, the Al2O3 content is set to a range of 6.90% to 12.00%. From a similar viewpoint, the Al2O3 content in the glass of this embodiment is preferably 7.00% or more, and preferably 11.80% or less.

[0028] <li2o> In the glass of this embodiment, Li2O is the component that reduces the viscosity of the glass melt and improves meltability among alkali metal oxides. However, if the Li2O content exceeds 8.00%, there is a risk that the thermal expansion coefficient of the glass will increase. On the other hand, if the Li2O content is less than 0.90%, there is a risk that the effect of reducing the viscosity of the glass melt and improving meltability will not be sufficiently obtained. For this reason, in the glass of this embodiment, the Li2O content is set to a range of 0.90% to 8.00%. From a similar viewpoint, the Li2O content in the glass of this embodiment is preferably 1.00% or more, and preferably 7.80% or less.

[0029] <na2o> In the glass of this embodiment, Na2O, though not to the same extent as Li2O, is a component that reduces the viscosity of the glass melt and improves its meltability. However, if the Na2O content exceeds 8.10%, the coefficient of thermal expansion increases, and there is a risk that the water resistance will deteriorate significantly. On the other hand, if the Na2O content is less than 0.90%, there is a risk that the effect of reducing the viscosity of the glass melt and improving meltability will not be sufficiently obtained. For this reason, in the glass of this embodiment, the Na2O content is set to a range of 0.90% to 8.10%. From a similar viewpoint, the Na2O content in the glass of this embodiment is preferably 1.00% or more, and preferably 8.00% or less.

[0030] <k2o> In the glass of this embodiment, K2O, though not to the same extent as Li2O and Na2O, is a component that reduces the viscosity of the glass melt and improves its meltability. However, if the K2O content exceeds 5.10%, there is a risk that the coefficient of thermal expansion will increase. Therefore, in the glass of this embodiment, the K2O content is set to a range of 0% to 5.10%. From a similar viewpoint, it is preferable that the K2O content in the glass of this embodiment be 5.00% or less.

[0031] <r2o> R2O represents the sum of Li2O, Na2O, and K2O. In the glass of this embodiment, the R2O content is 4.00% or more and less than 9.00%. If the R2O content is 9.00% or more, there is a risk that the thermal expansion coefficient of the glass will increase. On the other hand, if the R2O content is less than 4.00%, there is a risk that the effect of reducing the viscosity of the glass melt and improving meltability will not be sufficiently obtained. From a similar viewpoint, the R2O content in the glass of this embodiment is preferably 4.50% or more, and preferably 8.97% or less.

[0032] <mgo> In the glass of this embodiment, MgO is a component that can enhance the durability of the glass. However, if the MgO content exceeds 3.00%, the meltability of the glass may deteriorate. Therefore, in the glass of this embodiment, the MgO content is set to a range of 0% to 3.00%. From a similar viewpoint, it is preferable that the MgO content in the glass of this embodiment be 2.50% or less.

[0033] <cao> In the glass of this embodiment, CaO is a component that can enhance the durability of the glass. However, if the CaO content exceeds 3.00%, the meltability of the glass may deteriorate. Therefore, in the glass of this embodiment, the CaO content is set to a range of 0% to 3.00%. From a similar viewpoint, it is preferable that the CaO content in the optical glass of this embodiment be 2.50% or less.

[0034] <sro> In the optical glass of this embodiment, SrO is a component that can improve the devitrification resistance stability of the glass and enhance its durability. However, if the SrO content exceeds 4.00%, the meltability of the glass may deteriorate. Therefore, in the glass of this embodiment, the SrO content is set to a range of 0% to 4.00%. From a similar viewpoint, it is preferable that the SrO content in the optical glass of this embodiment is 3.50% or less.

[0035] <bao> In the glass of this embodiment, BaO is a component that can improve the glass's resistance to devitrification and enhance its durability. However, if the BaO content exceeds 4.00%, the meltability of the glass may deteriorate. Therefore, in the glass of this embodiment, the BaO content is set to a range of 0% to 4.00%. From a similar viewpoint, it is preferable that the BaO content in the optical glass of this embodiment is 3.50% or less.

[0036] <R’O> R'O represents the sum of MgO, CaO, SrO, and BaO. In the glass of this embodiment, the R'O content is 0% or more and less than 5.00%. If the R'O content exceeds 5.00%, the meltability of the glass may deteriorate. Furthermore, in the optical glass of this embodiment, the R'O content is preferably 4.50% or less from the viewpoint of further improving the durability and devitrification resistance of the glass.

[0037] <sb2o3> In the glass of this embodiment, Sb2O3 is a component that can degas the glass melt and can be added optionally. A Sb2O3 content of 1.00% or less is sufficient to obtain the effect of degassing the glass melt. For this reason, in the glass of this embodiment, the Sb2O3 content is set to a range of 0% to 1.00%.

[0038] <f> In the glass of this embodiment, F is a clarification accelerator. By including a small amount of F (for example, more than 0.01%) in the glass, degassing occurs and clarification is promoted. On the other hand, if the F content exceeds 1.00%, harmful fluorine volatiles may be generated and remain in the glass as bubbles. Therefore, in the glass of this embodiment, the F content is set to a range of more than 0.01% and less than or equal to 1.00%. Here, F can be incorporated into the glass by using fluorides such as KF, LiF, NaF, MgF2, CaF2, SrF2, BaF2, and AlF3 as raw materials.

[0039] <cl> In the glass of this embodiment, Cl is a clarification enhancer. When 0.05% or more of Cl is added to the glass, small bubbles expand and rise to the surface, promoting clarification. However, if the Cl content exceeds 1.00%, there is a risk of reducing the ultraviolet light transmittance. Therefore, in the glass of this embodiment, the Cl content is set to a range of 0.05% to 1.00%. Here, Cl can be incorporated into the glass by using chlorides such as KCl, LiCl, NaCl, AlCl3, MgCl2, CaCl2, SrCl2, and BaCl2 as raw materials.

[0040] <(R2O+R'O) / (SiO2+B2O3+Al2O3) mass ratio> The glass of this embodiment is required to have a mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) less than 0.1. Simply satisfying the above compositional requirements may not be sufficient to achieve both a low coefficient of thermal expansion and excellent water resistance. The glass of this embodiment can reliably achieve a low coefficient of thermal expansion by adjusting the content of components that increase the coefficient of thermal expansion (R2O and R'O) and components that decrease the coefficient of thermal expansion or do not affect the coefficient of thermal expansion (SiO2, B2O3 and Al2O3), that is, by making the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) less than 0.1. Therefore, the present invention can provide UV-C transparent glass that satisfies the above compositional requirements while having a mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) less than 0.1, thereby providing glass with good meltability, low thermal expansion coefficient, and excellent water resistance.

[0041] <fe2o3> Fe2O3 is a component that absorbs UV-C and may worsen UV-C transmittance. However, it is extremely difficult to completely avoid contamination from glass raw materials and manufacturing processes, and glass usually inevitably contains Fe2O3. Therefore, it is preferable that the glass of this embodiment has a low Fe2O3 content. Specifically, it is preferable that the glass of this embodiment has an Fe2O3 content of 0.01% or less, 0.005% or less, or 0.0005% or less. On the other hand, from the viewpoint of glass productivity, it is preferable that the glass of this embodiment has an Fe2O3 content of 0.00001% or more, or 0.0001% or more.

[0042] <tio2> TiO2, like Fe2O3, is a component that absorbs UV-C and may impair UV-C transmittance. However, it is extremely difficult to completely avoid contamination from glass raw materials and manufacturing processes, and glass usually inevitably contains TiO2. Therefore, it is preferable that the glass of this embodiment has a low TiO2 content. Specifically, it is preferable that the glass of this embodiment has a TiO2 content of 0.02% or less, 0.015% or less, or 0.01% or less. On the other hand, from the viewpoint of glass productivity, it is preferable that the glass of this embodiment has a TiO2 content of 0.0001% or more, or 0.0003% or more.

[0043] <Other ingredients> The glass of this embodiment may contain other components besides those listed above (SiO2, B2O3, Al2O3, Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, Sb2O3, F, Cl, Fe2O3, TiO2), as long as they do not deviate from the purpose. Examples of other components include Gd2O, Y2O3, La2O3, ZrO2, GeO2, Ta2O5, P2O5, etc. However, from the viewpoint of more reliably exhibiting the desired properties, the content of these other components is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less, and it is particularly preferable that the glass of this embodiment has a composition consisting only of the components listed above. Here, "consisting only of the above-mentioned components" means that the product substantially does not contain any impurities other than the above-mentioned components, specifically, the content of other components is 0.2% or less.

[0044] Cr2O3, NiO, CuO, CeO2, V2O5, WO3, MoO3, MnO2, and CoO are components that absorb UV-C and may impair UV-C transmittance. Therefore, it is preferable that the glass of this embodiment substantially does not contain these components.

[0045] Next, the various properties of the glass in this embodiment will be described.

[0046] <Melting property> In this specification, "melting property" refers to a phenomenon in which, by heating a uniformly mixed formulation raw material at the melting temperature, the vitrification reaction proceeds and a complete molten state is achieved without any unmelted material remaining. Since the glass of this embodiment has good melting property, its melting temperature is low, and it is also difficult for unmelted materials and / or bubbles to remain in the molten liquid. For the glass of this embodiment, for example, by heating the formulation raw material of the glass of this embodiment in an electric furnace at a melting temperature of 1450°C for 3 hours, a homogeneous glass without unmelted materials and / or bubbles can be obtained.

[0047] <Coefficient of thermal expansion> The coefficient of thermal expansion can be evaluated by measuring the average linear expansion coefficient (α 100-300℃ ). The average linear expansion coefficient is a physical property value representing the rate at which the length of an object changes corresponding to an increase in temperature, per degree of temperature, and is also called the coefficient of thermal expansion. Since the glass of this embodiment has a low coefficient of thermal expansion, when heat is applied to a part of the glass and the temperature difference within the glass becomes large, it is difficult for the glass to develop strain and is less likely to crack due to heat. From the perspective of making the coefficient of thermal expansion of the glass even lower, for the glass of this embodiment, the average linear expansion coefficient (α 100-300℃ ) is preferably 60×10 -7 / °C or less. From a similar perspective, for the glass of this embodiment, the average linear expansion coefficient (α 100-300℃ ) is more preferably 59×10 -7 / °C or less. Also, for the glass of this embodiment, the average linear expansion coefficient (α 100-300℃ ) is preferably 45×10 -7 / °C or more, and more preferably 46×10 -7 / °C or more. ​​​​​​) The adjustment of “)” can be carried out, for example, by appropriately adjusting the content of each component described above within a predetermined range and making the mass ratio represented by (R2O + R’O) / (SiO2 + B2O3 + Al2O3) less than 0.1.

[0049] <UV-C Transmittance> The glass of this embodiment has UV-C transmittance. The UV-C transmittance can be evaluated by measuring the internal transmittance at a wavelength of 265 nm with a glass thickness of 1 mm. Specifically, the glass of this embodiment can have an internal transmittance of 90% or more, and can also have an internal transmittance of 91% or more, at a wavelength of 265 nm with a glass thickness of 1 mm. Note that the above-mentioned “internal transmittance” is obtained in accordance with the calculation formula of JOGIS 17-2019 “Method for Measuring the Internal Transmittance of Optical Glass” of the Japan Optical Glass Industry Association Standard. Also, the adjustment of the “internal transmittance” of the glass of this embodiment can be carried out, for example, by appropriately adjusting the content of each component described above within a predetermined range.

[0050] <Glass Transition Point> The glass of this embodiment preferably has a glass transition point of 510 °C or lower. The glass transition point is the temperature indicating the process from the melt to the glass, and is also a temperature serving as an index for judging the feasibility of mold forming. When the glass transition point becomes high, the molding temperature also becomes high, and there is a risk of problems such as the glass adhering to the mold used and being unable to be demolded. Therefore, it is preferably as low as possible, and in the glass of this embodiment, it is more preferably 500 °C or lower, and even more preferably 490 °C or lower.

[0051] Note that the above-mentioned “glass transition point” refers to the temperature corresponding to the intersection of two tangents drawn from the low-temperature side and the high-temperature side of the bent portion in the thermal expansion curve measured in accordance with the Japan Optical Glass Industry Association Standard of JOGIS 08-2019 “Method for Measuring the Thermal Expansion of Optical Glass”. Also, the adjustment of the “glass transition point” of the glass of this embodiment can be carried out, for example, by appropriately adjusting the content of each component described above within a predetermined range.

[0052] <Water resistance> Water resistance can be evaluated by calculating the weight loss rate. In this specification, "weight loss rate" for glass refers to the weight loss rate (mass%) of a glass piece measuring 20 mm × 10 mm × 10 mm when the glass piece is boiled in 1000 ml of pure water for 60 minutes. The weight loss rate is calculated using the following formula. Weight loss rate = ("Mass of glass fragments before boiling" - "Mass of glass fragments after boiling") × 100 / "Mass of glass fragments before boiling"

[0053] The glass of this embodiment has excellent water resistance, and for example, it is preferable that the weight loss rate is less than 0.1% by mass.

[0054] The "weight loss rate" of the glass in this embodiment can be adjusted, for example, by appropriately adjusting the content of each of the above-mentioned components within a predetermined range.

[0055] (Method for manufacturing UV-C transparent glass) Next, the manufacturing method for the glass of this embodiment will be described. In this embodiment, the glass only needs to satisfy the above-mentioned range in the composition (content, mass ratio) of each component, and there are no particular limitations on its manufacturing method; it can be manufactured according to conventional manufacturing methods. For example, first, oxides, hydroxides, carbonates, nitrates, fluorides, chlorides, etc., are weighed in predetermined proportions as raw materials for each component that may be included in the optical glass of this embodiment, and thoroughly mixed to form the glass formulation raw material. Next, this glass formulation raw material is placed in a melting vessel that does not react with the glass formulation raw material (for example, a crucible of platinum group metals, platinum group metal alloys, quartz, etc.), heated to 1300-1450°C in an electric furnace to melt, and stirred as needed. After clarification and homogenization in the electric furnace, it is cast into a mold preheated to an appropriate temperature, and then slowly cooled in the electric furnace to remove distortion, thereby manufacturing the glass of this embodiment.

[0056] (Applications of UV-C transparent glass) The glass of this embodiment is not particularly limited in its use, but it is preferably used for precision mold press molding. Since the glass of this embodiment also has advantages in mold molding, by subjecting the glass of this embodiment to precision mold press molding, the glass parts described later can be easily manufactured.

[0057] (Glass parts) The following describes a glass component of one embodiment of the present invention (which may be referred to as "the glass component of this embodiment"). The glass component of this embodiment is characterized by using the aforementioned UV-C transparent glass as its material. Because the glass component of this embodiment uses the aforementioned UV-C transparent glass as its material, it has a low coefficient of thermal expansion and excellent water resistance.

[0058] The glass components of this embodiment are not particularly limited, but include LED cover lenses, lens arrays such as microlens arrays, prisms with lens functions, preform materials, fiber materials, etc. If the glass components include lenses, the lenses may be spherical lenses, aspherical lenses, plano-concave lenses, plano-convex lenses, biconcave lenses, biconvex lenses, concave meniscus lenses, convex meniscus lenses, microlenses, lenses with diffraction gratings, rod lenses, etc. Furthermore, the lenses may be provided with an anti-reflective coating, a wavelength-selective partial reflective coating, etc., on their surface as needed.

[0059] The method for manufacturing the glass component of this embodiment is not particularly limited, and a known method can be appropriately selected depending on the purpose. For example, the glass of this embodiment can be precision molded using a press molding method. [Examples]

[0060] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0061] The glass used in the examples and comparative examples was manufactured by the following method.

[0062] For each component in the compositions listed in Tables 1 to 8, the corresponding oxides, hydroxides, carbonates, nitrates, fluorides, and chlorides were used as raw materials, weighed to the desired proportions, and thoroughly mixed to form the raw materials for the formulation. Next, the raw materials were placed in a platinum crucible and melted in an electric furnace at a temperature of 1300 to 1450°C for several hours, while being stirred periodically with a platinum stirring rod to homogenize and clarify the mixture. After that, the mixture was cast into a mold that had been preheated to an appropriate temperature, and then slowly cooled in an electric furnace to obtain the glass for each example. In each example, AlF3 was used as the fluoride and NaCl was used as the chloride. Furthermore, the glass in each example had an Fe2O3 content of 0.01% by mass or less and a TiO2 content of 0.02% by mass or less.

[0063] Comparative Examples 1 and 2 correspond to the compositions of Examples 1 and 4 described in Patent Document 1 (Japanese Unexamined Patent Publication No. 4-342437), respectively, while Comparative Example 3 corresponds to Example 1 of Patent Document 2 (Japanese Unexamined Patent Publication No. 2018-197190). Comparative Examples 4, 5, and 6 correspond to Documents No. 1, 8, and 11 of Patent Document 3 (Japanese Unexamined Patent Publication No. 2012-140314). Furthermore, Comparative Example 7 corresponds to Example 1 of Patent Document 4 (Japanese Unexamined Patent Publication No. 2013-230952).

[0064] For each example of glass obtained, the fusion properties, thermal expansion coefficient, water resistance, and UV-C transmittance were evaluated, and the glass transition temperature was measured according to the following procedure. The results are shown in Tables 1 to 7.

[0065] <Evaluation of fusion properties> For the evaluation of moltenness, the blended raw materials were heated in an electric furnace at a temperature of 1450°C for 3 hours. If no unmolten material or bubbles were observed, the result was rated "A," and if unmolten material or bubbles were observed, the result was rated "B."

[0066] <Evaluation of thermal expansion coefficient> As an evaluation of the coefficient of thermal expansion, the mean linear expansion coefficient (α) 100-300℃ ) was measured. Specifically, the measurement of the average linear expansion coefficient (α 100-300℃ ) was performed according to the method described in JOGIS 08-2019 "Method for Measuring Thermal Expansion of Optical Glass" of the Japan Optical Glass Industry Association Standard. The smaller the value of such average linear expansion coefficient (α 100-300℃ ), the lower (better) the thermal expansion rate.

[0067] <Evaluation of Water Resistance> As an evaluation of water resistance, the weight loss rate was calculated. Specifically, the weight loss rate was calculated by the following method. The glass of each example was made into a glass piece of 20 mm × 10 mm × 10 mm, and the glass piece was boiled in 1000 ml of pure water for 60 minutes. Then, the weight loss rate was calculated by the following formula. The smaller the value of such weight loss rate, the better the water resistance. Weight loss rate = ("Mass of the glass piece before boiling treatment" - "Mass of the glass piece after boiling treatment") × 100 / "Mass of the glass piece before boiling treatment"

[0068] <Measurement of Glass Transition Point> The measurement of the glass transition point was performed according to the method described in JOGIS 08-2019 "Method for Measuring Thermal Expansion of Optical Glass" of the Japan Optical Glass Industry Association Standard. The lower the glass transition point, the better the moldability.

[0069] <Evaluation of UV-C Transmittance> As an evaluation of UV-C transmittance, the internal transmittance at a wavelength of 265 nm with a glass thickness of 1 mm was measured. Specifically, the calculation of the internal transmittance at a wavelength of 265 nm with a glass thickness of 1 mm was performed according to the method described in JOGIS 17-2019 "Method for Measuring Internal Transmittance of Optical Glass" of the Japan Optical Glass Industry Association Standard. The larger the value of such internal transmittance, the better the UV-C transmittance.

[0070]

Table 1

[0071]

Table 2

[0072] [Table 3]

[0073] [Table 4]

[0074] [Table 5]

[0075] [Table 6]

[0076] [Table 7]

[0077] [Table 8]

[0078] From Tables 1 to 3, the glasses of Examples 1 to 20 according to the present invention have a meltability evaluation result of "A" and an average linear thermal expansion coefficient (α 100-300℃ ) is 60 x 10 -7 The temperature was below / ℃, the weight loss rate was less than 0.10 mass%, and the internal transmittance at a wavelength of 265nm with a glass thickness of 1mm was 90% or more. From these results, it can be seen that the glasses of Examples 1 to 20 have good meltability, low coefficient of thermal expansion, excellent water resistance, and excellent UV-C transmittance.

[0079] Furthermore, the glass of Examples 1-20 had a glass transition temperature of 510°C or lower. This indicates that the glass of Examples 1-20 also has advantages in mold molding.

[0080] On the other hand, as shown in Tables 4 to 8, the glasses of Comparative Examples 1 to 33 do not meet any of the ranges defined in the present invention, and therefore are glasses with poor meltability, high thermal expansion coefficient, and / or poor water resistance.

[0081] The glass in Comparative Example 1 received a "B" rating for its fusion properties. This is thought to be due to its high SiO2 content and low B2O3 content.

[0082] The glass in Comparative Example 2 received a "B" rating for its fusion properties. This is thought to be due to its low B2O3 content.

[0083] Furthermore, the glass of Comparative Examples 1 and 2 had a low internal transmittance [%] at a wavelength of 265 nm at a glass thickness of 1 mm. This is thought to be due to the poor meltability of the glass of Comparative Examples 1 and 2, resulting in the retention of unmelted material and bubbles within the glass.

[0084] The glass in Comparative Example 3 had a meltability evaluation result of "B", and its average linear thermal expansion coefficient (α) 100-300℃ The glass of Comparative Example 3 had a high glass transition temperature. This is thought to be due to the high content of SiO2 and Na2O, and the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0085] The glass of Comparative Example 4 has an average coefficient of linear thermal expansion (α 100-300℃ The ratio was high. This is thought to be due to the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0086] The glass in Comparative Example 5 had a meltability evaluation result of "B", and its average linear thermal expansion coefficient (α) 100-300℃ The glass of Comparative Example 5 had a high glass transition temperature. These are thought to be due to the high SiO2 content and the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0087] The average coefficient of linear thermal expansion (α) of the glasses in Comparative Examples 6 and 7 100-300℃ The ratio was high. This is thought to be due to the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) being 0.1 or higher.

[0088] The glasses of Comparative Examples 8 to 25 have a mass ratio expressed as (R2O + R'O) / (SiO2 + B2O3 + Al2O3) that is less than 0.1, but the content of any of the components in these glasses does not meet the range of each component in the composition requirements.

[0089] The glass in Comparative Example 8 showed a large weight loss rate. This is thought to be due to its low SiO2 content and high B2O3 content.

[0090] The glass in Comparative Example 9 showed a particularly large weight loss rate. Furthermore, the glass in Comparative Example 9 underwent phase separation, and its internal transmittance [%] at a wavelength of 265 nm with a glass thickness of 1 mm was almost 0. These are thought to be due to an insufficient Al2O3 content.

[0091] The glass in Comparative Example 10 showed a large weight loss rate. This is thought to be due to the low Al2O3 content.

[0092] The glasses in Comparative Examples 11-13 received a "B" rating for fusion properties. This is thought to be due to their high Al2O3 content.

[0093] The glass of Comparative Example 14 received a "B" rating for its fusion properties. This is thought to be due to the fact that the glass of Comparative Example 14 does not contain Li2O.

[0094] The glass of Comparative Example 15 received a "B" rating for its meltability. This is thought to be due to the fact that the glass of Comparative Example 15 does not contain Li2O and has a low Na2O content. Furthermore, the glass of Comparative Example 15 had a low internal transmittance [%] at a wavelength of 265 nm with a glass thickness of 1 mm. This is thought to be due to the poor meltability of the glass of Comparative Example 15, resulting in the retention of unmelted material and bubbles within the glass.

[0095] The glass of Comparative Example 16 has an average coefficient of linear thermal expansion (α 100-300℃ The ) was high. This is thought to be due to the high K2O content.

[0096] The glass in Comparative Example 17 received a "B" rating for its fusion properties. This is thought to be due to its low R2O content.

[0097] The glass of Comparative Examples 18 and 19 had an average coefficient of linear thermal expansion (α 100-300℃ The sodium content was high. This is thought to be due to the high content of Li2O and the low content of Na2O.

[0098] The glass of Comparative Example 20 has an average coefficient of linear thermal expansion (α 100-300℃ The values ​​were high. These are thought to be due to the low content of Li2O and the high content of Na2O.

[0099] The glass of Comparative Example 21 has an average coefficient of linear thermal expansion (α 100-300℃ The weight loss rate was high, and the weight loss rate was large. This is thought to be due to the absence of Li2O and the high content of Na2O.

[0100] The glass in Comparative Example 22 received a "B" rating for its fusion properties. This is thought to be due to its high MgO content.

[0101] The glass in Comparative Example 23 received a "B" rating for its fusion properties. This is thought to be due to its high CaO content.

[0102] The glass in Comparative Example 24 received a "B" rating for its fusion properties. This is thought to be due to its high SrO content.

[0103] The glass in Comparative Example 25 received a "B" rating for its fusion properties. This is thought to be due to its high BaO content.

[0104] The glass of Comparative Example 26 has an average coefficient of linear thermal expansion (α 100-300℃ The ratio was high, and the weight loss rate was large. This is thought to be due to the high R2O content, resulting in a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of 0.1 or higher.

[0105] The glass of Comparative Example 32 has an average coefficient of linear expansion (α 100-300℃ The ) was high. This is thought to be due to the high R2O content, resulting in a mass ratio of (R2O+R'O) / (SiO2+B2O3+Al2O3) of 0.1 or higher.

[0106] Comparative Examples 27-31 and 33 are glasses that satisfy the composition requirements but have a mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) of 0.1 or more. The glasses of Comparative Examples 27-31 all have an average coefficient of linear expansion (α 100-300℃ The ratio was high. In addition, the glass of Comparative Example 33 had a large weight loss rate. From these findings, it can be seen that even if the composition requirements are met, if the mass ratio expressed as (R2O+R'O) / (SiO2+B2O3+Al2O3) is 0.1 or higher, it is not possible to achieve both a low coefficient of thermal expansion and excellent water resistance. [Industrial applicability]

[0107] According to the present invention, it is possible to provide UV-C transparent glass with good meltability, low coefficient of thermal expansion, and excellent water resistance in a specific composition of aluminoborosilicate glass. Furthermore, according to the present invention, it is possible to provide glass components using the UV-C transmitting glass described above. < / cl> < / f> < / bao> < / sro> < / cao> < / mgo>

Claims

1. In mass percent, SiO ２ : 46.90% or more and less than 55.00% B ２ O ３ 27.00% above 35.10% Al ２ O ３ 6.90% or more, less than 12.00% Li ２ O: 0.90% to 8.00% Na ２ O: 0.90% or higher, 8.10% or lower K ２ O: 0% or more, 5.10% or less R ２ O: More than 4.00% and less than 9.00% (however, R ２ O is the sum of Li ２ O, Na ２ O and K ２ O.). MgO: 0% or more and 3.00% or less, CaO: 0% or more and 3.00% or less, SrO: 0% or more and 4.00% or less, BaO: 0% or more and 4.00% or less, R'O: 0% or more and less than 5.00% (where R'O represents the sum of MgO, CaO, SrO, and BaO). Sb ２ O ３ : 0% or more, less than 1.00% F: more than 0.01% and less than 1.00%, Cl: 0.05% or more and 1.00% or less It contains, (R ２ O+R'O) / (SiO ２ +B ２ O ３ +Al ２ O ３ UV-C transparent glass characterized in that the mass ratio expressed as ) is less than 0.

1.

2. Average coefficient of linear expansion (α １００－３００℃ ) is 45 x 10 －７ / ℃ or higher 60 x 10 －７ The UV-C transmitting glass according to claim 1, wherein the temperature is below / ℃.

3. The UV-C transmitting glass according to claim 1 or 2, wherein the internal transmittance at a wavelength of 265 nm in a glass thickness of 1 mm is 90% or more.

4. The UV-C transparent glass according to claim 1 or 2, wherein the glass transition temperature is 510°C or lower.

5. The UV-C transparent glass according to claim 1 or 2, wherein the glass piece is 20 mm x 10 mm x 10 mm, and when the glass piece is boiled in 1000 ml of pure water for 60 minutes, the weight loss before and after the boiling treatment is less than 0.1% by mass.

6. A UV-C transparent glass according to claim 1 or 2, for use in precision mold press molding.

7. A glass component characterized by using the UV-C transparent glass described in claim 1 or 2 as a material.

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